Experimental Endocarditis Model of Methicillin Resistant Staphylococcus aureus (MRSA) in Rat

Summary

Experimental rat endocarditis model due to methicillin-resistant S. aureus.

Abstract

Endovascular infections, including endocarditis, are life-threatening infectious syndromes^1-3. Staphylococcus aureus is the most common world-wide cause of such syndromes with unacceptably high morbidity and mortality even with appropriate antimicrobial agent treatments^4-6. The increase in infections due to methicillin-resistant S. aureus (MRSA), the high rates of vancomycin clinical treatment failures and growing problems of linezolid and daptomycin resistance have all further complicated the management of patients with such infections, and led to high healthcare costs^{7, 8}. In addition, it should be emphasized that most recent studies with antibiotic treatment outcomes have been based in clinical settings, and thus might well be influenced by host factors varying from patient-to-patient. Therefore, a relevant animal model of endovascular infection in which host factors are similar from animal-to-animal is more crucial to investigate microbial pathogenesis, as well as the efficacy of novel antimicrobial agents. Endocarditis in rat is a well-established experimental animal model that closely approximates human native valve endocarditis. This model has been used to examine the role of particular staphylococcal virulence factors and the efficacy of antibiotic treatment regimens for staphylococcal endocarditis. In this report, we describe the experimental endocarditis model due to MRSA that could be used to investigate bacterial pathogenesis and response to antibiotic treatment.

Protocol

1. Preparing the MRSA Strains for Infection

1. Inoculate a loopful of MRSA culture from a stock tube at -80 °C to a sheep blood Trypticase Soy agar (TSA) plate (see Table of specific reagents and equipment), and incubate at 37 °C for overnight.
2. Check the purity of the culture on the blood agar plate (similar colony phenotypes) to make sure there is no contamination.
3. Pick one colony from the sheep blood TSA plate and inoculate the colony into 5 ml Trypticase Soy broth (TSB) in a 15 ml snap-capped tube.
4. Incubate at 37 °C overnight with shaking at 200 rpm.

2. Preparing Surgery Catheters

Discussion

The rat endocarditis is an important and well-characterized animal model for in vivo studies in the pathogenesis and antimicrobial agents in the treatment of bacterial infections ^9-11. In addition, rat endocarditis model represents a composite of acute and sub-acute infections, and closely mimics human counterpart and human native valve endocarditis. Moreover, accompanied by an in dwelling catheter, it represents a classic biofilm-associated infection, a common and difficult issue in clinical se.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Blood agar plate, 5% sheep blood in Trypticase Soy agar(TSA)	Hardy Diagnostics	A10BX
Trypticase Soy broth (TSB)	BD Biosciences	211825
Shaking incubator	Labnet International	I5311-DS
Polyethylene tubing	BD Biosciences	427401
Catheter introducer	BD Biosciences	6999
Isofluorance	Western Medical Suppy, Inc	2147	Follow safety and handling information
Surgical Instruments	Fine Science Tools and Biomedical Research Instruments, Inc.		Find the instruments from the two companies for your needs